Variable diameter pulley construction



Aug. 5, 1969 P. BARNISH T I 3,459,061

I VARIABLE DIAMETER PULLEY CONSTRUCTION Filed Aug. 30, 1967 3 Sheets-Sheet 1 INVENTORS PHILIP BARNISH ROGER B. BAERT Aug. 5, 1969 I BARNlSH ET AL VARIABLE DIAMETER PULLEY CONSTRUCTION 3 Sheets-Sheet 2 Filed Aug. 30, 1967 FIG.2

INVENTORS. PHILIP axuwwsn ROGER aasnr AGEN Aug. 5, 1969 p, BARMSH ET AL 3,459,061

VARIABLE DIAMETER PULLEY CONSTRUCTION Filed Aug. 30, 1967 3 Sheets-Sheet 5 PHILIP BARNIS ROGER B. BAERT BY iiwi. 1e- W AGENT United States Patent 3,459,061 VARIABLE DIAMETER PULLEY CONSTRUCTION Philip Barnish, Leeds, and Rober B. Baert, Sowerby, near Halifax, England, assiguors, by mesne assignments, to U.S. Philips Corporation, New York, N.Y., a corporation of Delaware Filed Aug. 30, 1967, Ser. No. 664,538 Claims priority, application Great Britain, Aug. 31, 1966, 38,894/ 66 Int. Cl. F1611 55/56 US. Cl. 74-23017 4 Claims ABSTRACT OF THE DISCLOSURE A pulley construction, having a fixed ball abutment member and a ball operated and axially movable pulley flange member. The pulley diameter can thus be varied and will depend upon the speed of rotation of the driving shaft.

The invention relates to domestic washing machines of the kind comprising a perforated washing drum rotatable about a substantially horizontal axis within a tub mounted in an outer casing or cabinet, the washing drum having an opening for the insertion (and removal) of the articles to be laundered and being adapted to be driven by an electric motor at a relatively slow rotational speed for tumble action washing and at a higher speed for spin drying of the articles.

In machines of the above described kind and to provide the necessary change in the rotational speed of the washing drum it is already known to use an electric polechanging motor in combination with a centrifugally operated expanding V-belt pulley. In such an arrangement the motor runs at its slower speed with the expanding pulley at its minimum diameter for driving the washing drum at a slow rotational speed, the motor being switched to its higher speed of rotation for spin drying with a consequent increase, due to centrifugal action, of the effective diameter of the expanding pulley, thus changing the gear ratio.

Centrifugally operated expanding pulleys suitable for the above described type of V-belt drive and employing balls as the centrifugal masses, are well known and are usually fabricated from cast or pressed metal parts, particularly those parts which coact with the balls. It has hitherto been considered necessary, in order to reduce wear, to make the ball coacting parts of hardened metal or to provide arrangements for ensuring that the balls do not traverse the same path repeatedly during operation of the pulley.

Fabrication of centrifugally operated expanding pulleys of these kinds is expensive and the object of the present invention is to provide an alternative construction which is relatively inexpensive and which is mechanically satisfactory for the duty involved.

We have discovered that it is possible to make a centrifugal ball operated expanding V-belt pulley suitable for domestic washing machines by making the parts normally subject to wear by the balls, i.e., one pulley flange and the abutment member for the balls, from conventional phenol formaldehyde synthetic resin having the normal fillers or extenders. Extended tests have shown that, even when the balls are each constrained so as to trace out the same path repeatedly when the pulley is expanded and contracted during use, the wear is not excessive. It has been found in fact that the balls tend to produce tracks in the form of depressions approximately 2-3 thousandths of an inch in depth during a first period of operation, whereafter there is a very greatly reduced wear on the parts. This may be due to some preliminary consolidation of the plastics material, but whatever the reason, pulleys of this kind have been found to be eminently satisfactory in practice.

The invention accordingly consists in a centrifugal balloperated expanding V-belt pulley for a washing machine, wherein the ball-operated axially movable pulley flange and the fixed ball abutment member are each moulded from a conventional phenol formaldehyde moulding composition.

Other features of the invention will be apparent from the following description, which is given by way of example only with reference to the accompanying drawings, in which:

FIGURE 1 shows a front elevation partly in section of a washing machineincorporating the invention,

FIGURE 2 is a side elevation, partly in section, to a larger scale of a washing machine motor driving and expanding V-belt pulley shown diagrammatically and FIGURE 3 is a perspective view of the moulded parts of the pulley.

In the drawings FIGURE 1 shows the main features of a Washing machine incorporating the invention. The machine has an outer casing or cabinet 1 within which is resiliently suspended a composite washing tub having the general reference 2, by means of four springs, only two of which, 3, 4, are shown in FIGURE 1. Vibrational movements of the tub are controlled by dampers 5, 6 extending between the tub and the base of the cabinet. A perforated washing drum 7 is rotatably mounted by bearing assemblies in the walls of the tub 2 and is driven by an electric motor 10 through a belt transmission including a centrifugal operated expanding pulley 15 on the motor shaft, a belt 11 driving a follower expanding pulley 12 acting as an idler pulley and a belt 13 engaging a pulley 14 on a shaft attached to the washing drum 7.

The expanding pulley 15 (FIGURE 2) is of substantially conventional design comprising an abutment member 16 keyed or otherwise secured to the motor shaft 17, a pulley flange 18 keyed or otherwise secured to the motor shaft and an axially movable pulley flange 19 which is driven by the abutment member 16. Centrifugal balls 20, which may be three in number, are arranged between the abutment member 16 and the movable flange 19. Each ball is constrained to move along a desired track, which may be radial, by webs forming part of either the abutment member 16 or the pulley flange 19. FIGURE 3 shows an actual constructional form in which the abutment member 16 and the axially movable pulley flange 19 are moulded from a conventional phenol formaldehyde moulding composition. The flange 19 is formed on the side opposite the belt engaging surface with three radial ball retaining pockets 26 at an angle of to each other. Extending between the outer ends of the pockets are cylindrical extensions 27, each having a slot 28. The abutment member 16 is in the form of a disc having a central hole 29 and a keyway 30 by which it may be nonrotatably secured on the driving shaft 17. Three ball coacting members 31 are moulded integrally with the disc 16 and each has a sloping face 32 providing a trackway for one of the balls 20. The disc 16 is also moulded with three driving dogs 33 each adapted to engage one of the slots 28 in the cylindrical extensions 27 of the flange 19 so that the flange 19 is constrained to rotate with the ball abutment member 16.

In FIGURE 2 the two extremes of movement of the axially movable pulley flange 19 are shown above and below the centre line of the motor shaft 17. The V-belt 11 (FIGURE 1) engages the expanding pulley 15 and the expanding follower pulley 12. The follower pulley 12 has a fixed flange 21 and axially movable flange 22, the flanges being urged towards one another by a spring 23. Since the belt 11 is of susbtantially invariable length the follower pulley 12 in the rest position of the parts has its flanges urged together by the spring 23 to the position shown below the centre line of the bearing unit 24 on which the pulley is mounted. In its rest position the balls 20 of the expanding pulley are at their innermost position and the pulley flanges are in the position shown above the centre line of the motor shaft 17. When the motor speed is increased the balls move radially outwards under the action of centrifugal force, causing the pulley flange 19 to approach the pulley flange 18, thus increasing the effective diameter of the pulley against the action of the spring 23, the follower pulley 12 being effectively reduced in diameter by movement of the pulley flange 22. Secured to or integral with the flange 21 of pulley 12 is an idler pulley 25 by which the drive is taken to the wash drum pulley 14 by the belt 13 (FIGURE 1).

The pulley flange 18 may also be fabricated as by moulding from a conventional phenol formaldehyde moulding composition which may include the usual fillers or extenders.

It will be understood that the invention is not limited to the exact constructional form described above since changes can be made to suit particular circumstances as they arise in practice, for example, the sloping faces 32 of the ball coacting member 31 and the corresponding pockets 26 in the polyflange need not be radially disposed, nor need the trackway provided by the faces 32 be flat. By suitable curvature of these faces, choice of the weight of the balls 20 and the rate of the spring 23, the motor speed at which the expanding pulley commences to operate and the rate of variation with increase of motor speed can to a certain extent be predetermined. Such relatively complicated curved surfaces can of course be readily reproduced when the parts are made from a conventional phenol formaldehyde moulding composition as envisaged by the invention.

We claim:

1. A variable diameter pulley for use on a driving shaft, comprising:

an abutment member, having means for attachment to the driving shaft,

a fixed pulley flange spaced from the abutment member and mounted on the shaft,

a movable pulley flange member mounted on the shaft between the abutment member and the fixed pulley flange;

means for aligning the abutment member and the pulley flange member to cause them to rotate together and also to permit axial movement of the pulley flange member with respect to the abutment member;

balls positioned between the abutment member and the pulley flange member,

pockets formed in the pulley flange member for containing the balls and restraining their movement, and

trackways formed on surfaces of the abutment member which slope radially outward and toward the pulley flange member, for coacting with the balls to cause same to displace the pulley flange member axially away from the abutment member as the balls are centrifugally moved outward on the sloping trackways.

2. The pulley as claimed in claim 1 wherein the means for aligning the abutment member and the pulley flange member comprises:

a cylindrical extension of the pulley flange member defining slots therein, and

dogs formed on the abutment member for engaging the slots and causing the pulley flange member to rotate with the abutment member, the dogs being axially slidable in the slots.

3. The pulley as claimed in claim 2 wherein the balls and the pockets for containing them are spaced apart around the pulley flange member.

4. The pulley as claimed in claim 3 wherein the abutment member and pulley flange member are made of a phenol formaldehyde synthetic resin.

References Cited UNITED STATES PATENTS 2,986,043 5/1961 Jaulmcs 74-23017 2,987,934 6/1961 Thomas 74-23017 3,010,333 11/1961 Rampe 74-230.17 3,142,997 8/1964 Rampe 74-23017 3,226,994 1/1966 Harley 74230.17

FOREIGN PATENTS 840,524 7/1960 Great Britain.

FRED C. MATTERN, 112., Primary Examiner J. A. WONG, Assistant Examiner 

